Experimental study on the dynamic properties of the dual-chamber solid and liquid mixture vibration isolator

2018 ◽  
Vol 24 (22) ◽  
pp. 5302-5311 ◽  
Author(s):  
FS Li ◽  
Q Chen ◽  
JH Zhou
Keyword(s):  
Liquid Mixture ◽  
Dynamic Properties ◽  
Liquid Column ◽  
Test Results ◽  
Equivalent Stiffness ◽  
Dual Chamber ◽  
Equivalent Damping ◽  
Fluid Damping ◽  
Equivalent Mass ◽  
Stiffness And Damping

The dual-chamber solid and liquid mixture (SALiM) isolator exhibits multiple stiffness and damping properties with various parameters. As a passive isolation device, the dual-chamber SALiM isolator can also obtain a variable stiffness property by substituting the valve with an active throttle device. Before that, the dynamic properties of the isolator need to be further investigated. Sine sweep tests under different valve openings were implemented to analyze the frequency response characteristics of the system. Two hydro pressure sensors were added into the two chambers to record the pressure signals, with which the equivalent stiffness, equivalent damping, fluid damping, and equivalent mass of the liquid column were identified. Based on the test results, numerical and theoretical analysis, the dynamic properties of the isolator including the influence of the fluid damping and inertia mass on the equivalent stiffness, the relation between the isolator's equivalent damping and the fluid damping, the fluid capacity of the linking tube, and the equivalent mass of the liquid column were analyzed in depth. Conclusions about stiffness and damping obtained from the test results correspond well with those from the theoretical analysis, but the identification results of the equivalent mass, which show that the negative correlation of equivalent mass of the liquid column with its response amplitude seems controversial. An assumption is proposed to explain the abnormal characteristics of the liquid column. However, the exact model of the inertia track needs further exploration and verification.

A Test Rig for Air Bearings Dynamic Characterization

2005 ◽  
Author(s):  
E. Bellabarba ◽  
R. Ruiz ◽  
S. Di´az ◽  
V. Rastelli
Keyword(s):  
Dynamic Properties ◽  
Excitation Frequency ◽  
External Diameter ◽  
Air Bearings ◽  
Equivalent Stiffness ◽  
Dynamic Characterization ◽  
Dynamic Forces ◽  
Present Design ◽  
Rotation Plane ◽  
Stiffness And Damping

This paper describes the design and operation of an experimental facility for measurement of equivalent stiffness and damping of air bearings. The rig uses two magnetic bearings to impose any given orbit to the journal, including displacement in two perpendicular directions on the rotation plane and tilting on the conical mode. Dynamic forces are measured directly on the test bearing housing. Data is gathered and processed using PC based data acquisition boards and software. Only the stiffness and damping coefficients of the fluid film are calculated as a function of the excitation frequency, being it synchronous or not. The present design allows testing air bearings up to 44 mm in external diameter and at frequencies up to 1 KHz. Preliminary testing was performed on this research that demonstrates the capability of the apparatus to measure the dynamic properties with ease and accuracy.

Influence of Equivalence Dynamic Parameters Variation About Behavior Structure of Milling Machine Tools

2007 ◽  
Author(s):  
Petru A. Pop
Keyword(s):  
Machine Tools ◽  
Experimental Tests ◽  
Dynamic Structure ◽  
Original Method ◽  
Milling Process ◽  
Milling Machine ◽  
Dynamic Parameters ◽  
Equivalent Stiffness ◽  
Equivalent Damping ◽  
Equivalent Mass

This paper has presented a study about behavior structure at universal precision milling machine for tool-shop by the variation of machine’s Equivalence Dynamic Parameters (EDP). These parameters of milling machine: equivalent mass – m [kg], equivalent damping constant – c [N/ms−1], equivalent stiffness – k [N/m], have been determined by experimental tests and from calculations, obtaining a exactly range values for each parts. All these had been calculated in function of eigenvalues of milling machine-ωn, which had been determined by experimental tests and mathematical model of dynamic milling process. For that, has been created an original program “Study mck”, which is used by SIMULINK program from MATLAB R14.v7.01 system. Then were executed 11 simulation tests, which were done by certain combinations of m, c, k values and cutting forces parameters, recorded approximately 300 diagrams. The results were significant has determined the chatter frequency very close to eigenvalues of machine by an original method, which had confirmed the experimental measures and analytical calculus and certain solution for improving the dynamic structure of milling machine by its equivalent dynamic parameters.

The Role of Air Damping in Synthesized Damping of Litchi Tree Vibration

2013 ◽  
Vol 295-298 ◽  
pp. 2041-2044
Author(s):  
Tian Hu Liu ◽  
Yu Xiang Luo
Keyword(s):  
Damping Ratio ◽  
Mass Range ◽  
Equivalent Stiffness ◽  
Trunk Length ◽  
Equivalent Damping ◽  
Air Damping ◽  
Air Resistance ◽  
Equivalent Mass ◽  
Canopy Size

In order to analyze the role of air damping in synthesized damping of litchi tree vibration, the fruit tree was simplified into a cantilever firstly. Then, according to equations of equivalent stiffness, equivalent damping, and equivalent mass, the damping ratio of air resistance was analyzed. The results showed that such damping ratio increases with the height of canopy center and the canopy size, and decreases with canopy mass and trunk radius. Within normal trunk radius, trunk length, canopy size, and canopy mass range, the damping ratio of air resistance is much smaller than 1.

The Dynamic Model of the Hoisting Monitoring Robot Using in Underground Coal Mine

2014 ◽  
Vol 1027 ◽  
pp. 282-285
Author(s):  
Yue Min Zhang ◽  
Yu Qing Wang
Keyword(s):  
Dynamic Model ◽  
Coal Mine ◽  
Surface Defects ◽  
Contact Stiffness ◽  
Equivalent Stiffness ◽  
Underground Coal Mine ◽  
Equivalent Damping ◽  
Exciting Forces ◽  
Stiffness And Damping ◽  
Robot Body

In this paper, regarding the monitoring robot body as the research object, the dynamic model of the monitoring robot hoisted on the monorail electric vehicle has been established with surface defects of I-steel rails as exciting forces. In this model, the contact stiffness and damping between the monorail electric vehicle’s wheels and rails have replaced with equivalent stiffness and equivalent damping.

scholarly journals Testing and Modelling of Elastomeric Element for an Embedded Rail System

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6968
Author(s):  
Qianqian Li ◽  
Roberto Corradi ◽  
Egidio Di Gialleonardo ◽  
Stefano Bionda ◽  
Andrea Collina
Keyword(s):  
Dynamic Properties ◽  
Reaction Force ◽  
Time History ◽  
Wide Frequency Range ◽  
Equivalent Stiffness ◽  
Zener Model ◽  
Elastomeric Material ◽  
Rail System ◽  
Non Linear ◽  
Stiffness And Damping

Modelling of elastomeric elements of railway components, able to represent stiffness and damping characteristics in a wide frequency range, is fundamental for simulating the train–track dynamic interaction, covering issues such as rail deflection as well as transmitted forces and higher frequency phenomena such as short pitch corrugation. In this paper, a modified non-linear Zener model is adopted to represent the dependences of stiffness and damping of the rail fastening, made of elastomeric material, of a reference Embedded Rail System (ERS) on the static preload and frequency of its deformation. In order to obtain a reliable model, a proper laboratory test set-up is built, considering sensitivity and frequency response issues. The equivalent stiffness and damping of the elastomeric element are experimentally characterised with force-controlled mono-harmonic tests at different frequencies and under various static preloads. The parameters of the non-linear Zener model are identified by the experimental equivalent stiffness and damping. The identified model correctly reproduces the frequency- and preload-dependent dynamic properties of the elastomeric material. The model is verified to be able to predict the dynamic behaviour of the elastomeric element through the comparison between the numerically simulated and the experimentally measured reaction force to a given deformation time history. Time domain simulations with the model of the reference ERS demonstrate that the modelled frequency- and preload-dependent stiffness and damping of the elastomeric material make a clear difference in the transient and steady-state response of the system when distant frequency contributions are involved.

scholarly journals A Magnetoelectric Hybrid Hydraulic Damper for the Mining Robot Suspension System

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Kun Hu ◽  
Fei Li ◽  
Zhiyuan Zhang ◽  
Shuang Wang ◽  
Hao Jiang
Keyword(s):  
Suspension System ◽  
Equivalent Stiffness ◽  
Vibration Displacement ◽  
Hydraulic Damper ◽  
Equivalent Damping ◽  
System A ◽  
Acceleration Amplitude ◽  
Working Principle ◽  
Stiffness And Damping ◽  
Suspension Structure

In order to improve the damping and controllability of the mining robot suspension system, a new magnetoelectric hybrid suspension hydraulic damper, which is a semiactive suspension damper, is proposed based on the traditional hydraulic damper by introducing the magnetic-electric hybrid suspension structure. The structure and working principle of the damper are introduced, respectively, and the mathematical models of the equivalent stiffness and equivalent damping of the system are calculated by the magnetic circuit method and the oil circuit method, while AMESim/Simulink cosimulation is carried out. In order to test the damping performance, a prototype of the magnetoelectric hybrid suspension hydraulic damper was fabricated. The results show that the vibration displacement amplitude can be reduced by 20% and the vibration acceleration amplitude can be reduced by 10% by adjusting the stiffness and damping of the system due to the magnetoelectric hybrid suspension structure. Moreover, the experimental results are consistent with the simulation results, which verify the effectiveness and superiority of this type of damper.

3 DOF Lumped Mass Tracked Vehicle Model

2015 ◽  
Vol 799-800 ◽  
pp. 803-807
Author(s):  
Mehmet Nuri Özdemir ◽  
Varlık Kılıç
Keyword(s):  
Degrees Of Freedom ◽  
Equivalent Stiffness ◽  
Vehicle Model ◽  
Lumped Mass ◽  
Tracked Vehicle ◽  
Matlab Simulink ◽  
System Parameters ◽  
Equivalent Damping ◽  
Equivalent Mass

A 3 DOF lumped mass tracked vehicle model was constructed in Matlab Simulink Environment and used for positioning the vehicle on gradients and missile firing operations. Pitch center, roll center and system parameters such as equivalent stiffness values, equivalent damping values and equivalent mass/inertias of 3 DOF model were obtained from 32+ degrees of freedom tracked vehicle model by simulations. Moments in pitch and roll directions were applied to the vehicle to find the pitch and roll centers. A range of step forces in bounce direction and a range of step moments in pitch and roll directions were applied to the vehicle and responses in the related directions of 32+ degrees of freedom model were used to determine the system parameters of 3-DOF model. Finally attitude of the vehicle on the gradients and missile firing scenario were simulated with both models and the results showed that 3 DOF model reasonably predicts the behavior of the tracked vehicle.

scholarly journals Identification of Dynamic Parameters of Pedestrian Walking Model Based on a Coupled Pedestrian–Structure System

2021 ◽  
Vol 11 (14) ◽  
pp. 6407
Author(s):  
Huiqi Liang ◽  
Wenbo Xie ◽  
Peizi Wei ◽  
Dehao Ai ◽  
Zhiqiang Zhang
Keyword(s):  
Negative Correlation ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Field Testing ◽  
The Body ◽  
Structural Vibration ◽  
Pedestrian Dynamics ◽  
Structure Interaction ◽  
Mass Spring ◽  
Stiffness And Damping

As human occupancy has an enormous effect on the dynamics of light, flexible, large-span, low-damping structures, which are sensitive to human-induced vibrations, it is essential to investigate the effects of pedestrian–structure interaction. The single-degree-of-freedom (SDOF) mass–spring–damping (MSD) model, the simplest dynamical model that considers how pedestrian mass, stiffness and damping impact the dynamic properties of structures, is widely used in civil engineering. With field testing methods and the SDOF MSD model, this study obtained pedestrian dynamics parameters from measured data of the properties of both empty structures and structures with pedestrian occupancy. The parameters identification procedure involved individuals at four walking frequencies. Body frequency is positively correlated to the walking frequency, while a negative correlation is observed between the body damping ratio and the walking frequency. The test results further show a negative correlation between the pedestrian’s frequency and his/her weight, but no significant correlation exists between one’s damping ratio and weight. The findings provide a reference for structural vibration serviceability assessments that would consider pedestrian–structure interaction effects.

scholarly journals Multi-Scale Study of The Small-Strain Damping Ratio of Fiber-Sand Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2476
Author(s):  
Haiwen Li ◽  
Sathwik S. Kasyap ◽  
Kostas Senetakis
Keyword(s):  
Dynamic Properties ◽  
Wide Spectrum ◽  
Damping Ratio ◽  
Polypropylene Fiber ◽  
Small Strain ◽  
Treatment Method ◽  
Fiber Content ◽  
Polypropylene Fibers ◽  
Test Results ◽  
Fiber Reinforced

The use of polypropylene fibers as a geosynthetic in infrastructures is a promising ground treatment method with applications in the enhancement of the bearing capacity of foundations, slope rehabilitation, strengthening of backfills, as well as the improvement of the seismic behavior of geo-systems. Despite the large number of studies published in the literature investigating the properties of fiber-reinforced soils, less attention has been given in the evaluation of the dynamic properties of these composites, especially in examining damping characteristics and the influence of fiber inclusion and content. In the present study, the effect of polypropylene fiber inclusion on the small-strain damping ratio of sands with different gradations and various particle shapes was investigated through resonant column (macroscopic) experiments. The macroscopic test results suggested that the damping ratio of the mixtures tended to increase with increasing fiber content. Accordingly, a new expression was proposed which considers the influence of fiber content in the estimation of the small-strain damping of polypropylene fiber-sand mixtures and it can be complementary of damping modeling from small-to-medium strains based on previously developed expressions in the regime of medium strains. Additional insights were attempted to be obtained on the energy dissipation and contribution of fibers of these composite materials by performing grain-scale tests which further supported the macroscopic experimental test results. It was also attempted to interpret, based on the grain-scale tests results, the influence of fiber inclusion in a wide spectrum of properties for fiber-reinforced sands providing some general inferences on the contribution of polypropylene fibers on the constitutive behavior of granular materials.

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